[UPDATE] Thank you all for bringing Nike+ sync problems to my attention. The API links have been broken since Nike+ released their new website. Unfortunately, the Nike+ APIs are not officially supported by Nike, so it is hard to say when the sync will work again
Sorry! I will be working to make it work as soon as possible.
[Update] Running Tracker is now working with the new Nike+ version! See the new post: http://runningtracker.tuxfamily.org/blog/2012/07/18/running-tracker-2-2-1/